GB1558987A

GB1558987A - Clamping device for a ram driven chainless haulage system

Info

Publication number: GB1558987A
Application number: GB5273176A
Authority: GB
Original assignee: Coal Industry Patents Ltd
Current assignee: Coal Industry Patents Ltd
Priority date: 1977-11-18
Filing date: 1977-11-18
Publication date: 1980-01-09

Description

(54) CLAMPING DEVICE FOR A RAM DRIVEN CHAINLESS HAULAGE SYSTEM (71) We, COAL INDUSTRY (PATENTS) LIMITED, a company organised in accordance with the laws of Great Britain of Hobart House, Grosvenor Place, London, SWiX 7AE, England, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to clamping devices for ram driven chainless haulage systems and in particular to clamping devices for ram driven chainless haulage systems to be used in the movement of mining machines along a track.

In mineral mining operations, especially in coal mining operations, a large amount of mineral is won using a system known as longwall mining. In this system a mining machine is mounted on a track and is traversed to and fro across the face of the seam which is being mined. As the machine traverses the face and wins minerals therefrom the track, usually a conveyor or an attachment thereto, on which the machine is moving is advanced towards the face, usually in a manner known as "snaking".

The track, or the conveyor, which guides the machine is associated with a series of roof supports through complementary advancing rams. Once the machine has cut a section of the face and passed on, the track behind the machine is advanced towards the face by extending the advancing rams. As soon as the track has been advanced the roof supports are advanced towards the track by retracting the advancing rams. This is the operation known as "snaking". Thus, once the machine has completed a traverse, the track has been advanced so that when the machine traverses in the opposite direction it is in a position adjacent the newly formed face ready to win coal.

The machine is traversed across the face either by a haulage chain or by chainless haulage. In the first case a chain is stretched along the face, the chain passing through the machine over a winch which drags the machine to and fro across the face along the chain.

Alternatively the winch is located at one of the face ends and the machine is attached to the chain, which is continuous, thus enabling the machine to traverse in either direction.

This type of haulage has many disadvantages.

For instance the movement of the machine is not usually very smooth, due to such factors as the elasticity of the chain, the varying hardness of the material in the seam, and the varying frictional force between the machine and the track. There is also a danger that the chain will break during operation, which is very hazardous for operatives in the vicinity of the machine. In this type of haulage the track, e.g. the conveyor, only serves to ensure that the machine follows a path adjacent the face.

To avoid the problems associated with the haulage chain, various types of chainless haulage have been developed. Two main types of chainless haulage are used, both of which involve the use of a track, which is normally mounted on, or at least associated with a face conveyor, which removes mined mineral matter from the face area. In the first type the track is constituted by a rack and the machine is provided with a driven pinion arrangement to form a rack and pinion type drive.

The second type of chainless haulage is ram propulsion haulage. The machine is attached either to the body or to the piston rod of two or more double-acting fluid operable driving rams, generally hydraulic rams.

The other ends of the rams are attached to clamping devices which are located around and engageable with the track. When a driving ram is actuated to extend the piston rod from the body it also acts to engage the clamping device with the track. With the clamping device engaged with the track, the extension of the piston rod acts to move the machine along the track. The ram is then actuated to retract the piston rod. This also releases the clamping device from engagement with the track, and so the clamping device is moved along the track. In normal operation there are a pair of driving rams which are operated out of phase so that while one driving ram is extending the other driving ram is retracting.

The retraction step may be carried out more quickly than the extension step and so it is possible to achieve smooth movement of the machine across the face by having the extension steps partly overlapping. Thus in the ram-driven type of chainless haulage as described above, the driving rams perform two functions, in that they cause the engagement of the clamping device with the track and they move the machine along the track.

However, it has been found that the force exerted by the driving rams is greatly in excess of the forces needed to effect engagement of the clamping device and to move the machine separately. Therefore the driving rams do not act efficiently, and draw more power than is necessary from the hydraulic or pneumatic power system.

It is an object of the invention to provide a ram-driven chainless haulage system which utilises the driving rams more efficiently and which therefore is able to use less power.

According to the present invention there is provided a clamping device to be used in a ram-driven chainless haulage system including a driving ram, comprising a bearing surface and a pivotally mounted abutment portion to be located on opposite sides of a track, and a double acting locking ram, operable independently of the driving ram, which locking ram is operable to pivot the abutment portion into and out of clamping engagement, in conjunction with the bearing surface, with the track.

The driving and locking rams are indepen dently either pneumatically or hydraulically powered.

The or each locking ram is located on the clamping device and is conveniently located such that the piston rod extends and retracts in a direction parallel or substantially parallel to the track of the haulage system.

The or each locking ram may also be located perpendicular or at any desired angle to the track, and may be connected to the abutment portion by a suitable lever system. The disposition of the locking ram is selected according to the practical requirements of the machine with which the clamping device is to be associated and the application of the machine. For example, in thin seams the horizontal arrangement is to be preferred to a vertical disposition in view of the height restrictions.

The locking ram is pivotally attached to the abutment portion and will only constrain the abutment portion in one direction; therefore as the clamping device includes at least two pivot points it will be necessary to provide locking means such that the abutment portion cannot be moved out of clamping engagement with the track except by the action of the locking ram. The locking means may comprise a guide associated with the abutment portion or may be further locking rams.

The bearing surface may comprise a stud or studs, or a rectangular pad of metal located on the clamping device in a position opposite the abutment means when the abutment means is in clamping engagement with the track.

Preferably the bearing surface is biased, conveniently by locating inside the bearing surface one or more springs or Bellville washers which engage the bearing surface and the clamping device, so that while the locking ram is actuated the bearing surface remains in contact with the track. This enables the clamping device to allow for any variations in the thickness of the track and for any tolerances built into the device.

Preferably, the clamping device has an interlocking control which operates such that no driving action is initiated until the clamping device is engaged, and that no acuon which moves the clamping device is initiated until the clamping device is out of engagement with the track. A suitable control, for a case where both the locking and the driving rams are hydraulically powered, is shown in our co-pending British Patent Application No.

2,005,752A.

By way of example only one embodiment of a clamping device according to the present invention will now be described with reference to the drawings accompanying the provisional specification, in which: Figure 1 shows a perspective view of a ram driven coal-mining machine including two identical clamping devices according to the invention, Figure 2 shows a plan view of the clamping device of Figure 1, Figure 3 shows a sectional side elevation along line I-I of Figure 2 of the clamping device with some parts removed for clarity, and Figure 4 shows an end elevation of the clamping device of Figure 2, with some parts removed for clarity.

Referring to Figure 1, a mining machine 1, in this case a ranging-drum shearer, runs along a track 2 and an upper flange 3 on face conveyor 4. The track 2 comprises a series of horizontal steel plates which are fixed to the face conveyor 4, which, in use, is posi tioned parallel and- adjacent to a coal face (not shown). The machine 1 is mounted on rollers 5 which run along the top of the track 2 and on the upper flange 3. The cylinders of two hydraulic double-acting rams 6, 7 are pivotally attached to the machine 1 and the piston rods 8, 9 are pivotally attached to two clamps shown diagrammatically at 10 and 11, respectively.

In Figures 2 to 4, to which reference is now made, no hydraulic connections are shown as these are well known in the art and need no further explanation. The clamping devices 10, 11 according to the invention are identical and each comprise two parallel spaced-apart metal plates 12, 13 one being somewhat longer and deeper than the other. The tops of the plates 12, 13 are aligned and therefore the plate 12 extends below plate 13. A base 14 is welded onto the bottom of plate 12 transversely thereof and extends across the space between the plates 12, 13. A channelled metal member 15 is welded onto the top of base 14, and a spring loaded pad 16 having a bearing surface 17 is located inside the channel of member 15. The pad 16 can execute a small degree of vertical movement but is stopped by the channel from execluting any horizontal movement.Springs 18, in the form of Bellville washers, act on the pad 16 and member 15 to bias the pad 16 upwards so that, in use, the bearing surface 17 is in contact with the bottom surface of the track 2. The small degree of vertical movement is made available to allow for both the tolerances of the component of the clamping device 10, 11 and the varying thickness of the steel plates which make up the track 2.

A double acting hydraulic locking ram 19 is pivotally secured centrally between the plates 12, 13 on a first bearing 20. The piston rod 21 of the locking ram 19 is pivotally attached to a locking member 22 which is pivotally mounted on a second bearing 23, located between the plates 12, 13. An abutment member, comprising two arms 24 pivotally attached to an abutment portion 25 by a cylindrical pin 26, is pivotally attached to the locking member 22 by a pivot pin 27 passing through the locking member 22 and the arms 24. The abutment portion 25 is a symmetrical fan-shaped cam having a minimum radius of curvature at the centre C of the abutting face.

The cylindrical pin 26 extends beyond the arms 24 of the abutment member and is located in two pairs of guides 28 welded onto the plates 12, 13. The guides constrain the cylindrical pin 26 to move in a vertical direction only. Bolts 29, 30 are provided between the plates 12, 13 both to ensure that the abutment member does not move too far, and to hold the clamping device together.

Two wheels 31 are also located between the plates 12, 13. The two wheels 31 are located on mounts 36, and may execute a limited degree of vertical movement, the limit being imposed by stops 37 located on axle-bearing parts 39. The wheels 31 are prevented from executing any rotational movement in the plane of the track 2 by pins 38 in mountings 36, which engage flattened portions 40 of the axle bearing parts 39. The wheels 31 are provided to enable the clamping device to move smoothly along the track 2 when the clamping device is not engaged therewith.

Two metal parts 41 are provided between the plates 12, 13 to provide support for the clamping device at the times during its movement along the track 2 when the wheels 31 have reached a gap between the steel plates comprising the track 2.

The arrangement is so designed that, in use, the abutment portion 25, the wheels 31 and the metal parts 41 are all located above the track 2, and the pad 16 is below the track 2. The piston rod 8 or 9 of one of the driving rams 6 or 7 is pivotally attached to the clamping device by way of pin 33.

As shown in Figure 3 and 4 the device is in clamping engagement with the track 2.

The spring loaded pad 16 ensures that both the pad 16 and the abutment portion 25 of the clamping device are engaged with the track 2, as long as the thickness of the track 2 is not so small as to be outside the tolerances of the clamping device. The abutment member is unable to move either in a horizontal direction, because of the guides 28, or in a vertical direction, because the pivot pin 27 is fixed in position by the locking ram 19. However, the abutment portion 25 is free to rotate about cylindrical pin 26. When a sliding force is applied to the abutment portion 25 by the track 2, perhaps due to the force exerted on the clamping device by the driving ram 8, the abutment portion 25 is induced to rotate.

As it does so, and in whichever direction it rotates, a portion of the abutting surface having an increased radius of curvature is brought into contact with the track 2, thus increasing the clamping force acting on the track 2.

This effect will occur as long as the locking ram is extended. It is therefore advisable to ensure that the locking ram remains extended if there is a power failure in the hydraulic system, so that the clamping device may operate as a brake if the driving power fails.

This is a very important safety aspect which may be incorporated into the device, and which is especially useful for the mining of inclined seams.

To disengage the abutment portion 25 the piston rod 21 of the locking ram 19 is retracted, causing the abutment member to swing in a clockwise direction (as viewed in Figure 3) around the axis of cylindrical pin 26, which itself will move vertically within the guides 28, thus swinging the abutment member in an elliptical path and out of contact with the track 2. The abutment portion 25 will remain with the point C as its lowest point due to gravity, in the arrangement as shown in the Figures. However, if the clamping device is located on a machine to be used for mining an inclined seam it may be necessary to supply a spring system or other biasing means to ensure that the point C of the abutment portion 25 is always the part of the abutment portion 25 closest to the track 2 when the clamping device is disengaged.

In order to move the machine 1 in the direction of arrow A in Figure 1 the following cycle of operations is repeated as many times as is necessary to complete a traverse of the face. As shown in Figure 1 neither of the clamping devices 10, 11 are engaged. Locking ram 19 of clamping device 10 is extended to bring the clamping device 10 into clamping engagement with the track 2. Piston rod 8 of driving ram 6 is extended, and, because the clamping device 10 is engaged, the machine 1 is moved in the direction of arrow A. During the extension of piston rod 8 of driving ram 6, the piston rod 9 of driving ram 7 is being retracted, and since the clamping device 11 is not engaged, the clamping device 11 moves along the track 2, mainly on the wheels 31, but where these cross gaps in the track 2, the clamping device travels on the metal parts 41.As soon as the piston rod 9 is fully retracted, the locking ram 19 of clamping device 11 is extended to bring the clamping device 11 into clamping engagement with the track 2. The driving ram 7 is then actuated to extend its piston rod 9 and therebv move the machine 1. As soon as the piston rod 8 of driving ram 6 is fully extended the locking ram 19 of clamping device 10 is actuated to free the clamping device 10 from engagement and the track 2 and the piston rod 8 of driving ram 6 is retracted, thereby moving the clamping device 10 along the track 2. When the piston rod 8 is fully retracted cycle is begun again. Preferably the retraction steps of the cycle are carried out faster than extension steps so that at all times at least one of the clamping devices 10, 11 are engaged with track 2, thus ensuring smooth movement of the machine 1 across the face.

In order to move the machine 1 in the opposite direction a smiliar cycle of operations is employed except that clamping devices 10, 11 are in clamping engagement with the track 2 while their respective driving rams 6, 7 are in the retraction step, and that the retraction steps take longer than the extension steps.

Although the clamping action of the clamping devices 10, 11 is totally independent of the driving action of the driving rams 8, 9, it is often desirable to provide an interlocking control for both sets of rams, such that no driving action is initiated until the appropriate clamping device is engaged, and that no action which moves the clamping device is initiated until that clamping device is out of engagement with the track. The control system may also be designed to ensure overlap of driving cycles so that smooth movement of the machine across the face is achieved.

The clamping action of the device is totally independent of the extension or retraction of the driving rams 6, 7. Thus more efficient operation of the system may be achieved, since the driving rams 6, 7 are only used for driving and the locking ram 19 is only used for lock ing the clamping device into engagement with the track.

WHAT WE CLAIM IS:- 1. A clamping device, to be used in a ramdriven chainless haulage system including a driving ram, the device comprising a bearing surface and a pivotally mounted abutment portion to be located on opposite sides of a track, and a double-acting locking ram, operable independently of the driving ram, which locking ram is operable to pivot the abutment portion into and out of clamping engagement, in conjunction with the bearing surface, with the track.

2. A clamping device according to claim 1, wherein the driving and locking rams are independently either pneumatically or hydraulically powered.

3. A clamping device according to either one of the preceding claims, wherein the locking ram is adapted to act along a line substantially parallel to the track.

4. A clamping device according to any one of the preceding claims, wherein the locking ram is connected to the abutment portion by a lever system.

5. A clamping device according to any one of the preceding claims, and including locking means whereby the abutment portion cannot be moved out of clamping engagement with the track except by action of the locking ram.

6. A clamping device according to claim 5, wherein the locking means is a guide associated with the abutment portion.

7. A clamping device according to claim 5, wherein the locking means is a further locking ram.

8. A clamping device according to any one of the preceding claims, wherein the bearing surface comprises at least one stud located on the clamping device in a position opposite the abutment means.

9. A clamping device according to any one of claims 1 to 7, wherein the bearing surface comprises a pad of metal located on the clamping device in a position opposite the abutment means.

10. A clamping device according to any one of the preceding claims, wherein the bearing surface is biased to move towards the track, so that while the locking ram is actuated the bearing surface remains in contact with the track.

11. A clamping device according to claim 10, wherein the bias is provided by at least one spring located between the bearing surface and the clamping device.

12. A clamping device according to any one of the preceding claims, and including an interlocking control adapted to operate the rams such that no driving action is initiated until the clamping device is engaged.

13. A clamping device according to claim

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. cycle of operations is repeated as many times as is necessary to complete a traverse of the face. As shown in Figure 1 neither of the clamping devices 10, 11 are engaged. Locking ram 19 of clamping device 10 is extended to bring the clamping device 10 into clamping engagement with the track 2. Piston rod 8 of driving ram 6 is extended, and, because the clamping device 10 is engaged, the machine 1 is moved in the direction of arrow A. During the extension of piston rod 8 of driving ram 6, the piston rod 9 of driving ram 7 is being retracted, and since the clamping device 11 is not engaged, the clamping device 11 moves along the track 2, mainly on the wheels 31, but where these cross gaps in the track 2, the clamping device travels on the metal parts 41.As soon as the piston rod 9 is fully retracted, the locking ram 19 of clamping device 11 is extended to bring the clamping device 11 into clamping engagement with the track 2. The driving ram 7 is then actuated to extend its piston rod 9 and therebv move the machine 1. As soon as the piston rod 8 of driving ram 6 is fully extended the locking ram 19 of clamping device 10 is actuated to free the clamping device 10 from engagement and the track 2 and the piston rod 8 of driving ram 6 is retracted, thereby moving the clamping device 10 along the track 2. When the piston rod 8 is fully retracted cycle is begun again. Preferably the retraction steps of the cycle are carried out faster than extension steps so that at all times at least one of the clamping devices 10, 11 are engaged with track 2, thus ensuring smooth movement of the machine 1 across the face. In order to move the machine 1 in the opposite direction a smiliar cycle of operations is employed except that clamping devices 10, 11 are in clamping engagement with the track 2 while their respective driving rams 6, 7 are in the retraction step, and that the retraction steps take longer than the extension steps. Although the clamping action of the clamping devices 10, 11 is totally independent of the driving action of the driving rams 8, 9, it is often desirable to provide an interlocking control for both sets of rams, such that no driving action is initiated until the appropriate clamping device is engaged, and that no action which moves the clamping device is initiated until that clamping device is out of engagement with the track. The control system may also be designed to ensure overlap of driving cycles so that smooth movement of the machine across the face is achieved. The clamping action of the device is totally independent of the extension or retraction of the driving rams 6, 7. Thus more efficient operation of the system may be achieved, since the driving rams 6, 7 are only used for driving and the locking ram 19 is only used for lock ing the clamping device into engagement with the track. WHAT WE CLAIM IS:-

1. A clamping device, to be used in a ramdriven chainless haulage system including a driving ram, the device comprising a bearing surface and a pivotally mounted abutment portion to be located on opposite sides of a track, and a double-acting locking ram, operable independently of the driving ram, which locking ram is operable to pivot the abutment portion into and out of clamping engagement, in conjunction with the bearing surface, with the track.

13. A clamping device according to claim

12, in which the control is adapted to operate the rams such that no action which moves the clamping device is initiated until the clamping device is out of engagement with the track.

14. A mining machine to be moved along the track, and including a pair of clamping devices according to any one of the preceding claims.

15. A mining machine according to claim 14 when dependent on claim 13, wherein the interlocking controls are adapted to operate such that the driving cycles of the two clamping devices overlap.

16. A clamping device substantially as hereinbefore described with reference to Figures 1, 2, 3 and 4 of the drawings accompanying the provisional specification.

17. A machine substantially as hereinbefore described with reference to Figures 1, 2, 3 and 4 of the drawings accompanying the provisional specification.